Jack Osbourne's MS diagnosis is the subject of People's new cover story.
In the magazine, he says he knew something was wrong last month.
His vision began failing, he says. "I couldn't see anything in front of me," Osbourne, 26, recalls, explaining that when he sought medical help for that problem, he received a - he suffers from multiple sclerosis.
MS was to blame for his vision loss - 80 percent in his right eye - Jack says. He's now beginning medication and adopting a healthier diet regimen to help reduce various symptoms of the disease, which attacks the central nervous system.
It can affect vision, movement and cognition, but luckily, his vision has already improved. "It's just one of those things you take as it comes," says Jack.
"It's all about your outlook."
His mom, Sharon Osbourne, opened up in an emotional interview as well, saying: "The first thing Ozzy and I asked ourselves was, 'What did we do wrong?'"
Nothing, but they're doing all the right things in standing by their son during a difficult time ... not that we'd expect anything less. Be well, Jack!